Nucleons after pion absorption

We calculate energy spectra and angular distributions of single and correlated spectra after the absorption of stopped pions in nuclei. We assume: The pion is abosrbed by a pair of nucleons; these primary nucleons may leave the nucleus directly or only after one or more collisions with other nucleons. We propose a multiple scattering expansion for the intranuclear cascade after pion absorption. Various experimental data are successfully described in shape and absolute magnitude. The ratio R_np = R(π^?np → nn)/R (π^? pp → np) is determined from the experimental proton spectra: R_np = 13 ± 6.     

Grazing incidence of short elastic waves on a slender cavity

The diffraction of high-frequency P waves incident along the axis of a slender cavity of finite length is investigated. The diffracted field can be divided into several regions. Near the cavity SV waves are generated by mode conversion but they are confined to two slanted strips on the sides of the cavity. The boundary layers along the edges of these strips are also studied. Diffraction of incident SV waves is also considered but the P waves generated by mode conversion affect only the immediate neighborhood of the cavity. Similar problems with a rigid slender inclusion are briefly discussed.     

Multi-aperture white light speckle method applied to the strain analysis of cylinders with holes under compression

Strain concentration factors of circular cylinders with circular and square holes are analysed by a white light speckle method. We introduce a four-aperture arrangement for recording white light speckles and find that the resulting isothetics are better in quality.     

Total cross sections of π, K, p and on protons and deuterons between 200 and 370 GeV/c

Total cross sections of π^±, K^±, p and on protons and deuterons have been measured at 6 momenta between 200 and 370 GeV/c.     

Addendum

Accurate valence band dispersions E$\text{k}$ of LaB₆ have been determined along three main symmetry lines ΓM, ΓX, and XM using one single crystal (001) surface by a simple new photoemission technique of general utility. Using direct interband transitions, E$\text{k}$dispersions are mapped out by suitably scanning polar emission angle and the photon energy. Detailed results agree well with recent Xα-APW energy band calculations.     

Temperaturkoeffizient der Polyäthylen-Ketten-Konfiguration aus Messungen der Intrinsieviskosität

Ohne Zusammenfassung     

Improved measurement of the K+-->pi+nunu; branching ratio

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211相似文献   

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.     

The use of the MNDO SCF MO method in UPS band-assignments for unsaturated hydrocarbons and fluorocarbons

The MNDO SCF MO method developed by Dewar and co-workers has been tested in regard to its ability to provide UPS band-assignments for a series of unsaturated hydrocarbons and fluorocarbons. The method performs admirably in this endeavour and generally predicts the same orbital-ordering scheme as that predicted by rigorous ab initio computational procedures. The possible use of the method in studying the “perfluoro effect” has been addressed as well. The method is clearly not as reliable for hexafluoro-(Dewar)benzene as for the other fluorocarbons. The MNDO predictions of the band assignments for the syn and anti dimers of cyclobutadiene serve to muddle further an already lively, but muddled, controversy.     

Exciton-contribution to the reflection spectrum at high excitation intensities in CdS

We report measurements of changes in reflection spectrum of CdS due to increasing the density of photoexcited carriers at temperatures above the critical temperature for electron-hole liquid formation. The contribution of the exciton resonance is seen to decrease and analysis of the lineshape indicates that this decrease is due to exciton-exciton collision and a change in exciton polarizability. These results are consistent with a transition from exciton to free electron-hole plasma (Mott transition) at a density of n ～ 2.5 x 10¹⁷ cm^-3.